Deadly soil-borne disease 'present in 79 countries'

Highest melioidosis risk zones are in South Asia, East Asia and the Pacific: Researchers

The bacterium that causes the deadly soil disease called melioidosis is more widespread than previously thought, researchers say.

In a paper published online in Nature Microbiology this week, researchers in Britain, Bangkok and the United States said melioidosis is likely present in 79 countries, 34 of which have never reported it.

The bacterium is present in soil, water and air across the tropics from Asia to northern Australia. It is so lethal that it is considered a potential biological weapon.

At the Mahidol Oxford Tropical Medicine Research Unit (Moru) in Bangkok, some 100 researchers and technicians study the bacterium in a Level 3 lab, which has, among other safeguards, a heavy double door. When the door is opened, air is allowed in, but never out. Lab technicians are clad head to toe in protective gear.

Melioidosis, spread by people as well as animals, has a low rate of incidence. It enters the human body through cuts on the skin, inhalation or by drinking contaminated water. Not everyone contracts the disease. A person can carry the bacterium for years before symptoms manifest themselves. But once they appear, the death rate is very high.

"Inadequate treatment may result in fatality rates exceeding 70 per cent," Moru said in a statement on Monday.

  • Facts on melioidosis

  • The bacterium: Burkholderia pseudomallei

    Where it is found: Soil, water and air

    How one gets infected: It is contracted through the skin, lungs or by drinking contaminated water

    How to detect it: The symptoms are easy to misdiagnose, so specific blood culture tests are needed.

    How dangerous it is: Mortality rate is 70 per cent without treatment

    How to treat it: With the drugs ceftazidime and carbapenem

    In Singapore in 2014, there were 34 cases of lab-confirmed melioidosis, compared with 36 in 2013, according to the Ministry of Health. There were two melioidosis-related deaths in 2014, or a case-fatality rate of 6.3 per cent, compared with 23.5 per cent in 2013. 

The use of two drugs - ceftazidime and carbapenem - has reduced mortality rates in Thailand to about 40 per cent and in Australia, to about 10 per cent.

The problem, however, is that the drugs are often not given because the disease is misdiagnosed. The disease mimics more common diseases and is thus difficult to detect with a standard blood test.  

"If you are in a rural area, say in Cambodia, and you have fever, they may take a blood test," said Dr Direk Limmathurotsakul, co-author of the paper, in an interview at Moru, where he is head of microbiology and an assistant professor at Mahidol University. 

"If it is not dengue, not malaria, they may just give you antibiotics... if you die... they'll say you died of blood intoxication."

 The study estimates that melioidosis killed 89,000 of the 165,000 people infected last year - compared with the annual global mortality from measles (95,000); leptospirosis (50,000); and dengue (12,500). High-risk groups include patients with diabetes mellitus, chronic kidney disease or excessive alcohol intake. The spread of diabetes in the tropics enhances the dangers of melioidosis, the paper says.  

"The highest melioidosis risk zones are in South Asia, East Asia and the Pacific, including all countries in South-east Asia and tropical Australia, sub-Saharan Africa and South America, with risk zones of varying sizes in Central America, southern Africa and the Middle East," the Moru statement said.

A version of this article appeared in the print edition of The Straits Times on January 13, 2016, with the headline 'Deadly soil-borne disease 'present in 79 countries''. Print Edition | Subscribe